enc0
pflog0
wan_stf
enc0 is the IPsec interface, pflog0 the packetfilter log device. You cannot remove them, they are built into OPNsense. Why would you? If you don't use them, ignore them.
No idea about wan_stf, though.
wan_sft is a little weird thing to enable 6RD on your WAN, which is probably configured (or 6to4 but it's nearly the same).
Cheers,
Franco